Talk:Transformer/Archive 6

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Archive 5 Archive 6 Archive 7

FA drive

Anyone interested in working this article up to FA status? Given its current (rather poor) state, there's a tremendous amount of work to do and text to remove or move out to other articles. — BillC talk 13:57, 1 April 2007 (UTC)

My intention is to move much of the transformer types text out to a separate article and reduce it to a summary here. I'm aiming for an article 40-45K in length. — BillC talk 23:35, 10 April 2007 (UTC)
I think that's a good idea, Bill. Alfred Centauri 02:11, 11 April 2007 (UTC)

I removed a lot (2K) of text at this edit. However, there had been an awful lot of repetition within that section, and reordering the paragraphs meant that much could be removed (IMO) without adversely affecting the content. Something I did cut back on was the treatment of EI core designs, surely unnecessary detail for this summary article. Perhaps better placed in an article dedicated to transformer cores, maybe. — BillC talk 07:35, 28 April 2007 (UTC)


No relative motion still means that the pri and sec windings could be rotating wrt a stationery body (like the earth)--- should this be clarified? —The preceding unsigned comment was added by (talk) 00:11, 2 May 2007 (UTC).

That wouldn't be relative motion "between its parts". — BillC talk 07:22, 2 May 2007 (UTC)


Efficiency varies widely depending on size; little "wall wart" transformers used to charge cell phones give off as much heat as they pass through, but a power transformer will typically have losses of only 0.25% or so - I've got some test reports here in my office! I don't think any transformer owned by a utility would be as low as 95%. This is one of the reasons why superconducting transformers haven't caught on; there's not much payback between 99.75% and 99.85% efficiency even on very large units, and the risks are significant. --Wtshymanski 21:54, 11 May 2007 (UTC)

That's interesting. The source I cited was fairly clear about its claims, though I admit 95% did seem a little low for a power distribution transformer. I'll have a look around, perhaps this weekend, and see if I can come up with some more references. Much (most) of the article is still inadequately referenced, though it's moving the right direction, albeit slowly. — BillC talk 22:47, 11 May 2007 (UTC)

That is just the kind of info I am looking for, that I would like to see in the article! (Graphs of efficiency vs. load for ordinary typical transformers of various sizes.) Unfortunately, you are not allowed to put your data in... But you could share more of it here on the talk page, and/or put it somewhere else and tell us where it is. And if you can find such info elsewhere, by someone else, than you could try to improve the article.

But the related and even more important point, that the article should clearly state, is that transformers consume/dissipate/waste power even when there is no load. Our residences tend to have a number of such small transformers, energized 24/7, consuming a few watts each -- and costing a few dollars each per year. For many small devices, this hidden life-cycle electricity waste can amount to more than the cost of the device.- 17:48, 29 May 2007 (UTC)

The other side of that, however, is that this "waste heat", plus that of incandescent light bulbs, refrigerators, etc., typically ends up heating the house/building, which in much of the US/world needs to be heated for half the year, anyway. Bad in the summer especially if you have to air condition it away, but in the winter it's just electric heat; more expensive than oil or gas, but potentially cleaner. (I have an old stove with a pilot light; I shut if off in the summer, but definitely leave it on in the winter)Gzuckier 18:53, 29 May 2007 (UTC)

I think this sentence under "Effect of frequency" is only applicable to 400Hz vs 50/60Hz transformers, with high frequency transformers used in switch mode power supplies being much more efficient than 50/60Hz ones. But can't find a reference.

  • "However efficiency becomes poorer with properties such as core loss and conductor skin effect also increasing with frequency."

There's a similar statement under "Winding resistance" which suggests greater resistance at higher frequencies. I think winding losses are usually less in high frequency transformers because they have fewer turns. But again no reference. Kallog 23:10, 8 July 2007 (UTC)

That's an interesting point, but the paragraph is discussing what happens to a given transformer as frequency increases. Comparing a ferrite transformer with a laminated-core power-frequency one is somewhat of a chalk-and-cheese comparison. Winding resistance increases at frequency due to skin effect: as the frequency increases, the current is progressively pushed into the outer edges of the conductor, increasing the current density there and increasing the losses. This is the case for any design of transformer. — BillC talk 00:29, 9 July 2007 (UTC)
The aircraft section talks about increasing the frequency making it more compact, so its not a given transformer. I certainly got the impression it was saying transformers designed for high frequencies are less efficient than low, which in my experience is wrong - it may even be wrong for 400Hz, the reference doesn't feel very reliable. Regarding the second section, it isn't clear that it's talking about a given transformer. I don't really think that was the intention, so it's misleading at best. Kallog 12:35, 9 July 2007 (UTC)
Trying to state that a transformer designed for 400 Hz (or 300 kHz, or whatever) is necessarily more or less efficient than a transformer designed for 50/60 Hz is nonsense. A competent transformer designer can make you pretty much any efficiency you ask for at pretty much any frequency (though the cost and size might not be reasonable). Reasonable things to talk about would be what happens to a given transformer, or what is typical. And rather than debating which the article means, we should make it explicitly say one or the other...or include both discussions. My opinion about what's typical is that higher frequency transformers are more efficient. That's because they are smaller, and in both cases, the designs are typically constrained by heat. And the smaller transformer can't dissipate as much heat for a given temperature rise, so it has to be designed for lower loss.

Ccrrccrr 02:21, 10 July 2007 (UTC)

OK, good point. Even better than talking about it is just change it and see if anyone reverts it, which is what I've done. Kallog 07:15, 10 July 2007 (UTC)
I support the edit, and won't be changing it. I'll see if I can find a better citation than the current one. Regards, — BillC talk 12:03, 10 July 2007 (UTC)


Hi, do you mind if I do something with this edit? It's not well-placed, you see, slipped in between two headings, and it's mostly repeating things that are written further down in the article. — BillC talk 10:48, 13 May 2007 (UTC)

The trouble is, that the rest of the article (Parasitic capacities, losses, most of construction) deals mainly with (single) coils, this does not even belong in this article. Then there is a section about leakage that should really fill a lot of space in the article. The current introduction is strange. Mutual induction is often introduced for parallel wires and the real introduction to leakage would be to show a trifilar wound transformer. But most people stumble over the flux through the core. The ideal transformer is said to have negligible net magnetization current, jet significant magnetic flux is induced. The equations even claim that the net magnetization current is exactly zero. But at another place it is said how the current through the primary coil induces a flux. And a lot of people think that there is a lot of flux in the core if a transformer is only lightly loaded. This seems to be a difficult topic, and I think any really interested reader will be happy to be freed from the paradox as fast as possible. Arnero 19:42, 13 May 2007 (UTC)

To deal with one of your statements here, if I understand you correctly, you think the article is contradicting itself with its treatment of magnetising current. The explanation given here is the same as that presented in the references, and is that current flowing in the primary circuit creates MMF, which is the source of the flux. The time-varying flux induces a voltage on the secondary winding and on the primary (a 'back EMF'). The equations do not claim that the magnetising current is zero, but instead take it to be negligible and ignore it. I'm not sure if I understand what you meant by "a lot of people think that there is a lot of flux in the core if a transformer is only lightly loaded". Are you saying those people are right, or wrong? — BillC talk 20:30, 13 May 2007 (UTC)
Try pulling the core out of a small transformer when it's energized and not delivering any current to an external load --*something* is holding that core in with a mighty buzz. I always thought this was a pretty good demonstration of flux. ( Of course, if you do pull the core all the way out, the winding will then draw too much current.) --Wtshymanski 17:52, 20 June 2007 (UTC)


If you only use one half of the transformer would it act as an inductor? User: -Ozone-

Yes, it would, though the ideal transformer approaches infinite inductance. (The Reference Desk is probably the best place for such questions, though.) — BillC talk 09:42, 20 May 2007 (UTC)
Sorry, hadn't thought of the reference desk, with infinite inductance wouldn't it be impossible to have any current flow? Or is it that it is almost infinite inductance, if that is the case around what inductance would they have?Ozone 02:31, 21 May 2007 (UTC)
If you look at the equivalent circuit with the secondary open-circuit, the ideal transformer has Rp=Xp=Rs=Xs=0, and Rc (modelling core loss) infinite, hence no core losses. Then, as per the article, Ip=I0=magnetising current, which is very low. The only way for the magnetising current to be very low is for Xm to be very high, i.e. approaching infinity. The maths tends to break down if you say it is infinite, though. Regards, — BillC talk 07:32, 21 May 2007 (UTC)
Ozone: infinite inductance does not imply zero current through the inductor. Instead, it implies zero change in current through the inductor. That is, an ideal inductor 'looks' like, in the limit as the inductance goes to infinity, an ideal constant current source. Alfred Centauri 13:23, 21 May 2007 (UTC)


I think auxiliary cooling losses are always considered and charged against the transformer capital cost; I've seen a few utility specs that call for this. Maybe we need a power transformer article so that this one can concentrate more on the physics and basic theory? --Wtshymanski 01:57, 19 June 2007 (UTC)

There's no question at all that such losses need to be accounted for as part of the cost of ownership, but I think that they should not be considered a part of the technical losses. Perhaps an side article might be called for: it could consider the total losses in transformers, examine the economics of superconducting windings or amorphous steel, and so on. What physics and basic theory do you think should be in this article that are not already? — BillC talk 19:52, 19 June 2007 (UTC)

High frequency power transformers

It seems odd that this type of transformer is completely absent from the article. Was that done on purpose? They're clearly important because they're used to power nearly every computer, TV, etc. They're not described on the Switch-mode power supply page either which might be a more relevent place. Any ideas if we should write something? Kallog 23:32, 8 July 2007 (UTC)

There's no question that there are a lot of transformer types that might be mentioned here. However, space is short, and this article has suffered in the past from some sections getting over long. For this reason, I split off a large section into Transformer types. That might be a better place to add a new one, with perhaps an article of its own linked from there. — BillC talk 23:58, 8 July 2007 (UTC)

Trying to help out, per Awadewit

Hi Bill,

Thanks very much for fixing my errors in the lead this morning. My friend Awadewit asked me to come here and help out with a semi-educated lay-person's perspective. I'll make a few well-intended changes, but you should feel free to fix or revert them as you think best. With admiration for all your work here, Willow 17:39, 16 July 2007 (UTC)

Change of sign

The sign of the primary and secondary voltages in the recent edits is incorrect according to the diagram associated with that section (see Fig 2-6 on pg 57 of "Electric Machinery, 5th edition). Alfred Centauri 14:02, 17 July 2007 (UTC)

I was striving for consistency with Faraday's law of induction. Please remember that the time derivative of cosine is the negative sine.
As an aside, the "average" flux meant "averaged over the coils" rather than "averaged over time". The flux through the turns of a winding need not be exactly the same. Hoping that this helps clarify my intentions, Willow 17:52, 17 July 2007 (UTC)

Concerns about recent edits

In the recent edits, much is made about the phase relationship between the secondary voltage and the primary current. However, the given relationship (complete with a chart) is only true when the secondary is unloaded which is arguably not how most transformers are used.

I propose to remove that part of the section completely. Alfred Centauri 14:11, 17 July 2007 (UTC)

I can't agree to the removal, although I understand your point. My goal was only to stay close to the original (unloaded) derivation, and then discuss deviations in the loaded case. I'm sure that we can find a good compromise. Willow 17:54, 17 July 2007 (UTC)
I have some problems with the lead into "Technical points". It says that the preceding section assumes negligible reluctance. This is in fact the assumption of the following section, in which the concept of the magnetic circuit and magnetomotive force are discussed. The prior section at times assumes zero magnetising current (for example in assuming the equality of apparent power on both sides), and at others non-zero (for example in the graph). Further to Alfred Centauri's comments, the graph is only true for an unloaded transformer with neither leakage reactance nor winding resistance, and with non-zero reluctance. — BillC talk 21:15, 19 July 2007 (UTC)
It's fine to remove the graph, although my own preference would be to have multiple I-V graphs, for idealized unloaded and loaded cases. The "negligible reluctance" quote came from the July 15th version (cited below). To my memory, I didn't really contribute anything to the "Technical points" section or below that; I only contributed to the lead, and sections 1-1.2. The "technical points" section was, I thought, just the remnants of what had been in the original exposition that was covered in my sections; I didn't want to delete anything that had been in the original. I see now that I did delete a "magnetizing current" sentence, which I'm sorry for. For the newbie, though, it might be better to go directly from the primary current IP to the secondary voltage VS via Faraday's law, and then go back and discuss the relationship between VP and IP. Willow 21:44, 24 July 2007 (UTC)
This is the text that was removed:

The current develops an MMF over the secondary winding in opposition to that of the primary winding, so acting to reduce the flux in the core.[1] However, any decrease in the flux reduces the back EMF, and so disturbs the equilibrium of the primary circuit.[2] The primary current rises, increasing the core flux until the primary EMF has again matched the supply voltage, at which point the effect of the secondary MMF has been exactly offset.[3]

The core flux and both primary and secondary EMFs thus remain the same regardless of the secondary current, and are instead determined by the magnitude of the primary voltage, provided that voltage is sustained.[1] The primary winding acts as a load to the primary circuit, and the secondary winding as a voltage source to the secondary. By this means, electrical energy fed into the primary circuit is transferred to the secondary.

The primary and secondary MMFs differ only to the extent of the contribution by the negligible magnetising current and so approach equality: .[2] If these terms are equated, thereby ignoring the magnetising current, then the transformer current relationship emerges:

BillC talk 23:27, 24 July 2007 (UTC)
I find the whole rewrite to be much more problematic than the circa July 15 version, in which the voltage relationship was derived without reference to current. As it stands now, many of the equations don't apply at all to an actual transformer as used in practice (with a loaded secondary), or to an ideal transformer (in which magnetizing current is zero and a bunch of the equations used become zero times infinity. I'm tempted to revert to the ~July 15 version unless someone can explain what was wrong with that version.Ccrrccrr 20:53, 24 July 2007 (UTC)
I can only speak for myself, but I found even this introductory paragraph taken from the 15 July version
mostly incomprehensible, and I sort of understand transformers. I'm sure that a practicing transformer engineer would have no trouble with all that, but such a reader is unlikely to come to Wikipedia for an explanation of how a transformer works, don't you agree? Transformers seem simple enough that there's a hope of explaining them to conscientous but non-engineer readers such as Awadewit and myself, and I think we should strive for that. I certainly don't claim to know transformers better than you all, but please be patient with my mistakes and please let us give you some insight into how the previous version was difficult to understand. Willow 21:26, 24 July 2007 (UTC)
Thanks! That's the insight I was asking for. To me, the quoted July 15 paragraph is comprehensible, elegant, simple, and direct, whereas the boxed "text that was removed" above is overly convoluted. I would suggest that we take the old July 15 version and re-write it using more lay terminology and less jargon, but stick to the same outline and equations to describe how it works--incremental improvements in clarity rather than a new explanation which actually more convoluted. But I'm a little unsure about the question of the audience. We can have a relatively qualitative explanation, and a mathematically careful explanation, some readers will stop with the qualitative one, whereas others will delve into the mathematical one. I guess your take on that is the the mathematical can use concepts from calculus and first-year college physics, but not specialized terms like reluctance and MMF?Ccrrccrr 01:29, 25 July 2007 (UTC)

missing core info

  • pot cores are an important core geometry in small transformers
  • there needs to be a discussion of core saturation
  • effect and use of core gaps needs to be mentioned

AJim 03:38, 18 July 2007 (UTC)

Technical level

Willow asked me to look at the beginning of this article again after she edited it. My major concern is that the article is still too technical.

  • Take the equations out of the lead. That is going to scare many people away.
  • The secondary circuit mimics the primary circuit, but its current and voltage need not have the same magnitudes as those of the primary. - is the bit "magnitudes" necessary for the lead? Many people will not know "magnitudes" of what exactly.
  • Since the energy lost over the transmission is proportional to the square of the current, transformers allow electricity to be transmitted more efficiently. - I would save such mathematical explanations for later.
  • I would take all of the mathematics out of the "basic principles" section, especially since it appears to have some calculus in it (the "d", right?). (Did I say this before? I don't remember.)
  • What do you think about a "Basic mathematics of transformers" of "Basic mathematics of electromagnetism" section? Awadewit | talk 17:52, 23 July 2007 (UTC)
I've removed the reference to magnitudes in the lead. I think the formulae may be helpful, since mathematical explanations in words can be hard to follow. As for the "Basic principles" section, removing the mathematics would essentially remove all the content. Instead, I would propose to rename the section (e.g. "Theory of transformers") and move it to later in the article. This may require adding new first section on "Basic principles", but these principles should be really basic (essentially expanding on the basic principles discussed in the lead per WP:LEAD). Geometry guy 19:01, 23 July 2007 (UTC)
That sounds like a promising idea. Awadewit | talk 09:05, 25 July 2007 (UTC)

Different order of presentation early on?

I'd like to suggest a slower and somewhat different way of introducing the lay-reader to transformers. My feeling is that the (sometimes complex) properties of the core might be distracting for readers who are still trying to understand the basic idea. So my suggestion would be to clarify the concepts of electromagnet and induction first, and show how these combine to make the ideal transformer. I think those two concepts might be readily understood by lay-people, especially if well-illustrated. Perhaps we could have three Figures, one of a pure electromagnet (one red winding, no core), one of pure induction (one blue winding, no core), and a third of both windings coaxial, so that it seems plausible to the reader that the same flux passes through both windings. I could try to draft simple versions of these Figures as a starter.

Once the basic "vacuum-core" transformer idea is clarified, then we can introduce a material core, discuss its advantages (such as lowering flux leakage) and drawbacks (saturation, frequency dependence, etc.). That prepares the reader to understand the basic differences among the various transformer types and geometries, and start to get at the real engineering going on.

I would also recommend that the article be very conservative with unfamiliar terminology, especially early on. I have at least a little familiarity with electromagnetism, but I've never heard of magnetic reluctance until now. I (sort of) follow the Wikipedia article, but the magnetomotive force is still a little mysterious; is it the same as magnetic scalar potential? I'd recommend that, early on, we restrict ourselves to more commonly taught concepts such as impedance, resistance, reactance, inductor, that sort of thing; once it's all understood, then we can introduce the reader to MMF and reluctance as an alternative approach used by practicing engineers (true?).

Can we also agree on a sign for Faraday's law? I'm pretty sure that the negative sign is correct, although we should be consistent, whatever we decide upon.

Let's take it slow, too, talking things over here, reaching consensus and then transferring that consensus to the article. I'm sorry for having been hasty before. Willow 21:07, 24 July 2007 (UTC)

Thank you for your message here. Magnetomotive force is the effect which gives rise to a magnetic field. Mathematically, it is the closed-loop integral of the B-field in a plane normal to the loop (and divided by μ). More usefully, it is a very important concept in transformer (and inductor) design because, expressed in ampere-turns, it is easily calculable from the current and number of turns in the primary winding. It is not magnetic scalar potential, but is analogous to voltage. As voltage drives a current around an electric circuit, MMF drives magnetic flux around the magnetic circuit. Reluctance is analogous to resistance: it determines the flux that will result from an MMF. Hence in an unloaded transformer, we have a magnetic circuit equation analogous to its electric circuit counterpart:
However, unlike resistance, reluctance is not a source of power loss.
As regards the sign in Faraday's Law (or Lenz's Law), Hindmarsh (a standard reference for electrical engineering undergraduates for many years) discusses this. "The negative sign... indicates this opposition, but it will be found to be more convenient when writing down the circuit equations, to use a positive sign and treat the EMF as a back emf". This is why the 'ideal transformer as a circuit element' is drawn as it is, and is discussed briefly in the text under 'Technical points'.
For structure, I suggest a simplistic description of the transformer, perhaps stating without derivation the ideal transformer equation:
and then a section called 'Mathematical analysis' or such, where we can go into more detail. — BillC talk 22:10, 24 July 2007 (UTC)
Willow, I agree in general with the slow intro. One problem though is that the ideal transformer equation that Bill presents above does not apply to an air-core (vacuum, whatever, it doesn't matter) example, so the ideal core assumption (which you can call infinite permeability if you want to stay away from relucutance) actually makes the analysis simpler, rather than more complex. I'm not sure of the best approach.
The place to look to learn about reluctance, MMF, etc., should be the magnetic circuit article, but I actually don't like that article, because I think of magnetic circuit as a simplifying assumption, that allows lumped analysis of magnetics (a shortcut to avoid using maxwell's equations directly), just as electric circuits are simplifying assumptions that allow lumped analysis as a shortcut to avoid direct application of maxwell's equations for electrical stuff. To answer your scalar potential question, the relationship between scalar magnetic potential and MMF is the same as the relationship between electric potential and voltage. Potential is a concept in field theory, whereas MMF and voltage are concepts in lumped analysis. But they are pretty much the same thing.
If the magnetic circuit article were better, there could be a section of the transformer article that explained the operation in those terms, with someone new to that concept referred to the mag circuit article first. With of course a simpler explanation not relying on those concepts coming first. Ccrrccrr 01:50, 25 July 2007 (UTC)

Thanks for pointing me to the magnetic circuit article, which was fun reading. :) The dual equivalence of magnetic field lines B and electrical current density J seemed to open up a little window in my brain; I had a sudden vision of the field lines of a bar magnet resembling the the flow of ions in a conducting solutions, as in the action potential. I always had trouble with the latter, so visualizing them as magnetic field lines was very helpful.

I'm still a little unclear on the definition of magnetomotive force. From Bill's comment above, it's defined as a closed-loop line integral

Did I understand that correctly? If so, we should add this definition to the MMF article, since this definition seems better defined and more general than

I'm a little confused, though, because the MMF should be a vector, not a scalar, by Ampere's law; its value seems to depend on the size and orientation of the loop around which it's being calculated.

(deep breath) Anyway, now that I understand the concept a little better, I'd like to persuade you that we shouldn't use such MMF/reluctance concepts in the initial descriptions of how a transformer works. Elegant and simple though its wordings may be, this approach seems too foreign for all but engineers specializing in magnetics and too demanding for most readers to absorb on the fly. I'm not sure that we can expect them to even know basic electromagnetism, so a cute but recherché alternative description seems just too much, don't you think? I fear that the dual equivalence thing will be lost on most people.

How about this compromise? All of us seem to be converging on the idea of a stepwise introduction to how transformers work. How about having three explanations of ever greater complexity? We could begin with an initial non-mathematical one (lead + initial blurb), followed by a basic mathematical one, and finally one involving MMF and reluctance for the cognoscenti. For the second one, I agree with Ccrrccrr's suggestion that we limit it to what students might be learn in a late-high-school or freshman-college physics course with calculus. Willow 15:55, 25 July 2007 (UTC)

I agree with that compromise.
MMF is like voltage in that a circuit might have a source with some voltage and then some resistors in series, each of which "drop voltage". The voltage across the resistors adds up to the MMF source. The MMF source in a magnetic circuit is usually a coil (though it could be a permanent magnet). Then that MMF is dropped across perhaps a few reluctances. The integral you've defined counts all the places that MMF is dropped across reluctances, but doesn't count the source. If you count both the total around the loop will be zero. But my main objection to the integral definition is that MMF needn't be a closed loop--it is normally defined for one element of reluctance, or for one coil, etc. Then Kirchoff's voltage law applies, and you add up each of them and get zero overall. Ccrrccrr 02:15, 26 July 2007 (UTC)

Air-core transformer

I'll confess that I'm a bit enamored of the idea outlined above for introducing transformers as "transformer = electromagnet + induction" and stripping away the complications of the material core. Is there a problem with that approach beyond flux leakage? I was thinking that, for the idealized illustration of how transformers work, we could make the primary and secondary windings coplanar loops, so that the flux through the primary should (plausibly) equal the flux through the secondary. Willow 16:16, 25 July 2007 (UTC)

A small point, but I would refrain from describing the exciting winding being an 'electromagnet'. I don't think in 21 years I have heard the primary winding of a transformer described as being an electromagnet. — BillC talk 17:35, 25 July 2007 (UTC)

Yes, perhaps it's a distraction. I introduced the term only because some readers might remember electromagnets from their childhood science classes; "electromagnet" might speak to them more vividly, more memorably, than if we simply say "current in a coil produces a magnetic field". Willow 18:06, 25 July 2007 (UTC)

Having two windings very close to each other does make leakage very small. Adding a core actually doesn't reduce the absolute value of leakage inductance. It just increases magnetizing inductance so that leakage becomes small relative to magnetizing inductance, even though leakage doesn't get smaller. So I am fine with drawing them close together and saying leakage is negligible. Co-planar doesn't necessarily mean close together, or necessarily mean low leakage.
But the real difference between an ideal transformer and an aircore transformer is that the ideal transformer current relationship
doesn't hold or even come close to holding, because primary current is largely magnetizing current, which is probably about 90 degrees out of phase with secondary current.
Someone with physics background and no engineering background might be happier not learning about the ideal transformer current relationship, and instead understanding the voltage relationship in an unloaded air-core transformer. But I think that transformers are primarily an engineering topic not a physics topic, and for engineering, the behavior of an unloaded air-core transformer is not of interest, and is misleading, because the current relationship in a real practical transformer is closer to the behavior described by the ideal transformer equation.
An idea would be to make a new article, "air-core transformer," which would explain the operation in this way. The main transformer article could refer physics-oriented folks who want that kind of explanation to that article, where it would be clear that the analysis doesn't apply to the thing on the utility pole outside your house.
Similarly, the magnetic-circuit analysis of transformer operation could be split off somewhere, perhaps into a new article titled magnetic-circuit analysis.
I just looked up WP guidelines on article size, and 30 to 50 KB is recommended; we are at 53. So by that measure, it would make sense to split some of this off.Ccrrccrr 02:39, 26 July 2007 (UTC)
Perhaps an article on mutual induction (currently a redirect to inductance) would be a good place for analysis of the air-core transformer. — BillC talk 18:08, 27 July 2007 (UTC)

Can I just check whether my basic assumptions are correct?

  • Faraday's law holds regardless of whether the core is air or not. If we assume that the magnetic field is always linear in the current IP in the primary coil (no saturation, etc.), then

holds for some constant k. Changing the core changes the constant k, but not the form of the equation, as long as the magnetic field flux through the secondary coil ΦS is linear in the current.

That's true only if the secondary current is zero. The field is linear w.r.t. current, yes, but that means
Ccrrccrr 14:29, 31 July 2007 (UTC)
  • For a lossless transformer, the time-averaged incoming power must equal the time-averaged outgoing power, right?

This also holds regardless of the core, as long as the core is lossless, no? I can see how this equation might not hold instantaneously, since some energy in the magnetic field will build up and decline periodically, but the equation should hold when averaged over a full cycle, no?

Yes, but if you want to write what you say precisely, you need to be careful of things like the fact that the time average of the product of v(t) and i(t) is different from the product of the time averages of v(t) and i(t). In other words, your statement above the equation says the right thing, but the equation either says something different and is wrong, or is vague and doesn't capture the detail that your words do, depending on how you interpret it. It is not necessary to get into phasors, impedance, or power factor to write the equation correctly--just transcribe your words carefully into mathematical notation (which I'd do for you but I don't know very well how to do that in wiki form). Ccrrccrr 14:29, 31 July 2007 (UTC)

If those two assumptions are incorrect, then I really need to re-evaluate my participation here. More generally, I think I need to read up on this subject more before I can contribute meaningfully; I'll do my best over the next few weeks. I still believe that the basic principles of transformers can be explained to non-engineers in intelligible language without treating it like a black box, but that dogged hope might wither once I learn more. Willow 19:08, 27 July 2007 (UTC)

I think you're assuming that all the primary current is transformed to the secondary. To illustrate this, consider the case of an air-cored transformer with an open-circuit secondary. Our 'transformer' thus consists of an air-cored inductor with an open circuit coil hanging around nearby. The secondary current is zero, because the secondary winding is open-circuit. The primary current consists only of the magnetising current. The primary current's RMS value will be the RMS voltage divided by the reactance of the air-cored coil, and the voltage and current will be 90° out of phase from each other. Clearly under these circumstances, we cannot say that the equation: holds, even if the arrangement is, on average, lossless. — BillC talk 22:36, 27 July 2007 (UTC)
Additionally, it is the assumption that IP is in phase with IS that is in error. The conservation of power equation really is:
where Re denotes 'the real part of', and I* is the complex conjugate of I. — BillC talk 11:42, 28 July 2007 (UTC)

Hi, thanks very much for the clarifications; I'm beginning to see where I've been going astray. Let me check one more thing, if you would be so kind. If we attach a load of impedance ZS (which may be frequency dependent) across the secondary, then the equation

should hold, provided that the load is a linear system; these variables are the (complex) Fourier transforms of their time-domain counterparts such as IS(t) and VS(t).

I'm asking this only because I think this is where I'm going astray; personally, I think that we should avoid complex quantities/phasors, at least in the initial sections for lay-people. Transformers seem hard enough to understand without introducing complex voltages and currents; I suspect most people would feel confused by them. Leibniz says that complex numbers are "amphibians caught halfway between Being and Non-Being"; do you measure an imaginary current with an imaginary meter? ;)

I'll stop by again in a few days; I need to read up some more before I can feel that I have a clue. But I'm trying sincerely, and I hope you can hang on a little longer. Willow 21:22, 30 July 2007 (UTC)

This article has had a long and rather tortuous history over the years, but I don't think there has ever been a treatment of Fourier transforms and phasor relationships within it. I'm not seeking one for the article now. The pre-July 15 version for example, didn't. To answer your question, yes, the equations hold true for complex (but linear) loads. Regards, — BillC talk 21:50, 30 July 2007 (UTC)
Yes, you can avoid phasors, etc. In particular, once assume some complex impedance for a load, the analysis only applies to linear loads. But many transformers are used with nonlinear loads, such as rectifiers (perhaps even a majority of transformers). The fundamental equations describing the transformer must not depend on the load being linear, even if they assume (in the ideal case) that the transformer itself is linear.
Note that I added some comments directly below your equations in your previous comment, which I think should be helpful.Ccrrccrr 14:29, 31 July 2007 (UTC)

Basic Principles simplificiation

As reflected in the extended discussion above, starting with "Concerns about recent edits", the "basic principles" section has been somewhat problematic and potentially misleading. The main problem, as I see it, was that it discussed primary current creating a field without noting the fact that secondary current also contributes to the field. Many solutions were discussed. I hope the discussion will be continued and a better explanation developed, but in the meantime, I wanted to at least remove the misleading parts of the existing article, so I went ahead with an edit, which simplified the discussion by not bringing primary current in quantitatively. Ccrrccrr 17:30, 12 August 2007 (UTC)

Problematic intro

This is the current version of the intro:

A transformer is a device that transfers electrical energy from one circuit to another through a shared magnetic field. A changing current in the first circuit (the primary) creates a changing magnetic field; in turn, this magnetic field induces a voltage in the second circuit (the secondary). By adding a load to the secondary circuit, one can make current flow in it, thus transferring energy from one circuit to the other.

Here are the technical problems I see with this:

(1) Electrical energy cannot be transferred by a magnetic field alone. The energy is transferred within the transformer via an electromagnetic field as is clearly explained in this link from the article [[1]].
(2) The second sentence starts out with "A changing current in the first circuit..." and then the third sentence starts out with "By addind a load to the secondary circuit...". But, as is well known for an ideal transformer, there is no current through the primary circuit if the secondary circuit is open. Yes, there is a magnetizing current in a physical transformer and this can indeed be made to change independently of the secondary load however, the (changing) primary current that leads to energy transfer to the secondary circuit load is not independent of the load and is in fact due in part to the presence of the secondary load.

Thoughts or proposals? Alfred Centauri 18:52, 12 August 2007 (UTC)

The solution is to be clear with the distinction between magnetising current and load current. Since the 'Basic principles' section has now been redacted, confusion between the two has been reduced, though not altogether eliminated from the article. With regard to the intro, a little more laxness of wording can be tolerated in the lead section, though of course that doesn't mean we should be wrong. — BillC talk 23:24, 12 August 2007 (UTC)

Static, passive

A transformer may be considered static because, unlike an electric machine (motor or generator), it doesn't have moving parts. It may be considered passive, because unlike a switching power converter it does't have active devices such as semiconductors. The recent edit deleting static didn't reflect an understanding of this; hence my comment here. Ccrrccrr 21:13, 2 December 2007 (UTC)

Wrapping a coil around a magnetic field? Crazy

Since all magnetic fields extend to infinity, how can you wrap a coil round one ccrrccrr? Please reinstate my edit which makes far more sense than the present version.--TreeSmiler (talk) 15:13, 5 January 2008 (UTC)

Im intending to reinstate my edit unless I get a sensible answer ccrrccrr!--TreeSmiler (talk) 19:05, 6 January 2008 (UTC)

Sorry--didn't see your question. I think the first figure in the article shows a two coils (red and blue) wrapped around a field (green). I think that at the level of basic principles that is an understandable concept. I agree that your description was more rigorous, but I think it's more helpful to readers to keep the "basic" section basic, and put the rigorous description in the "technical details" section or later. We've had complaints (see discussion above) from people who thought the concept of how a transformer worked was something that isn't that hard to understand, but found the explanation here to be full or jargon. The idea of having the basic principles section is to explain it at an understandable level, not to have a bulletproof physical/mathematical description. I'm not particularly fond of the wording that is there, so feel free to experiment with improvements, but understand the reason for the structure that's there. If you think the structure should be changed, feel free to explain your thinking, and make some edits towards that end. But if you agree with the structure and want to make improvements within that structure, that section should be optimized for for ease of understanding at a basic level, and the rigor nitpicking should go later.Ccrrccrr (talk) 19:29, 6 January 2008 (UTC)

We must avoid jargon, but we must be accurate, esp in the lede--TreeSmiler (talk) 01:00, 8 January 2008 (UTC)

Looks like Neparis has done just that while we've been wasting our time on the talk page!Ccrrccrr (talk) 03:19, 8 January 2008 (UTC)

Transformer ratings

What does 70VA/90VA mean in practical terms? You don't need to explain the power factor since I know about it. All I want to know is what that 70/90 ratio means.

ICE77 (talk) 21:17, 5 January 2008 (UTC)

I don't think I've ever seen a power ratio like that mentioned on a transformer. Perhaps it refers to two different situations, such as operation at 50 Hz or 60 Hz? Could you post the full set of information that you drew those numbers from? --Gerry Ashton (talk) 21:20, 5 January 2008 (UTC)
The ratings for a secondary with two output taps? - Neparis (talk) 00:31, 6 January 2008 (UTC)
Na na. Its the core that sets the VA rating (saturation flux density and all that)--TreeSmiler (talk) 00:35, 6 January 2008 (UTC)
Air cored? ;-) Neparis (talk) 02:53, 6 January 2008 (UTC)
Although air does not saturate (as far as I know) it is difficult to obtain sufficient magnetic coupling between two windings if you dont have a core. But Im sure someone will prove me wrong.--TreeSmiler (talk) 18:59, 6 January 2008 (UTC)
RF? - Neparis (talk) 20:05, 6 January 2008 (UTC)
What are typical coupling coefficients at RF? Any I said magnetic coupling not electromagnetic interaction!--TreeSmiler (talk) 18:11, 7 January 2008 (UTC)
Coils with air cores are magnetically well coupled if L / λ ≪ 1. - Neparis (talk) 00:32, 8 January 2008 (UTC)
Ah well thats RF for you. We were talking mains frequency as I recall.--TreeSmiler (talk) 00:40, 8 January 2008 (UTC)
Er, RF includes mains frequency. - Neparis (talk) 02:28, 8 January 2008 (UTC)
I dont think many engineers would agree with that from a practical viewpoint, as the techniques in involved in handling these different frequencies is ,er,.. quite different.--TreeSmiler (talk) 20:34, 8 January 2008 (UTC)

The 70VA/90VA figure comes from a transformer I used when I built a stereo some years ago. Unfortunately, that is the only piece of information I can supply. What I can add is that after the power was 120Vrms and that after the transformer there was a full-wave bridge rectifier that was feeding some power amplifiers with an input of +35V. That might help you help me.

ICE77 (talk) 10:57, 6 January 2008 (UTC)

I'd suggest asking the manufacturer, through the email link on their site [2].Ccrrccrr (talk) 12:39, 6 January 2008 (UTC)
You could also try asking one of these three guys who by an amazing coincidence used a "70VA/90VA" center-tapped 120V-50V stepdown transformer in a project at California State University, Northridge to build a stereo amplifier. - Neparis (talk) 17:19, 6 January 2008 (UTC)
Um, the coincidence may not be that amazing. — BillC talk 18:10, 6 January 2008 (UTC)
Sorry, tongue in cheek :) - Neparis (talk) 20:02, 6 January 2008 (UTC)

Right, one of those three guys is me. At the time we didn't mark done all of the specifications for the transformer. We might have written down something wrong. That's why that 70VA/90AV still puzzles me. I requested the document that describes the transformer to the manufacturer. Maybe I will be able to solve the mystery soon. If you have any suggestions they will be appreciated in the meanwhile.

ICE77 (talk) 13:44, 7 January 2008 (UTC)

I would think Gerry Ashton's suggestion of operation at two frequencies is the best yet; though for 50/60Hz one would expect a ratio of 75/90 VA (or 70/84 VA). — BillC talk 17:59, 7 January 2008 (UTC)

Correct me if i'm wrong. Transformer are rated in kVA but not in kW, shouldn't the reasons be included in the article? Lambda driver (talk) 04:56, 21 August 2008 (UTC)

Mistake in Ideal Power Equation ("The impedance in one...")

The following is incorrect:

The impedance in one circuit is transformed by the square of the turns ratio.[1] For example, if an impedance ZS is attached across the terminals of the secondary coil, it appears to the primary circuit to have an impedance of . This relationship is reciprocal, so that the impedance ZP of the primary circuit appears to the secondary to be .

The first equation should be, in order to satisfy Ohm's Law. To see how this works use the equation, on the a simple circuit. If N_S/N_P give a Voltage scale-up my factor 10, then the current must go down by a factor 10... and so the impedance in the second coils must be higher than the first. —Preceding unsigned comment added by Erlendd (talkcontribs) 21:44, 10 February 2008 (UTC)

I don't think it's wrong. Consider a transformer with a turns ratio of Np:Ns = 1:10. We apply 10V to the primary, and so 100V appears across the secondary (which is initially open-circuited). We then place a 1kΩ resistance across the secondary. The secondary current = 100/1000 = 0.1A. In the primary, 10×0.1 = 1A flows. The primary sees a 1A current with 10V potential difference, which means it thinks there is a resistance of 10/1 = 10Ω. The primary therefore sees the secondary impedance transformed by a factor 10/1000 = 1/100 = (1/10)2 = (Np/Ns)2. — BillC talk 22:20, 10 February 2008 (UTC)
Actually, on reading your message more carefully, I think it is a case of you misreading the article, because we have just said the same thing: the secondary impedance is larger. However, the article says that the secondary impedance appears to the primary to have been scaled down by a factor of 102. In other words, the voltage source of the primary circuit can't tell the difference between a 1kΩ resistor applied to the secondary circuit of a 1:10 ratio transformer, and a 10Ω resistor applied to the primary circuit (without any transformer). — BillC talk 23:02, 10 February 2008 (UTC)

I wrote this comment as BillC was writing his latest comment, and it says about the same thing:

Erlendd, when you say "the impedance in the second coils must be higher than the first", I think you mean that the impedance connected to the secondary winding must be higher than the impedance seen at the primary. That's exactly what the equation in the article says for your example. I think it's just a problem of interpreting the terminology in the article.Ccrrccrr (talk) 23:05, 10 February 2008 (UTC)

You're right - the article is fine. I looked it up in a textbook to be sure. —Preceding unsigned comment added by (talk) 00:00, 21 February 2008 (UTC)

Energy Losses, Eddy Currents.

To quote the last sentence from Energy Losses, Eddy Currents. “The eddy current loss is a complex function of the square of supply frequency and inverse square of the material thickness”. Which is clearly misleading as it would mean that increasing the thickness would reduce eddy current loss. I thought eddy current losses in laminae was proportional to the square of frequency, the square of thickness and the inverse of the resistivity.--King of Tea Tree (talk) 11:09, 2 June 2008 (UTC)

parallel operation

is it possible to connect Yy0 transformer with Dy11 transformer in parallel? explain —Preceding unsigned comment added by (talk) 13:11, 25 June 2008 (UTC)

This sounds like a homework problem. --Gerry Ashton (talk) 13:39, 25 June 2008 (UTC)

Homemade Iron Core transformer

Adding something on how to build one from a solid iron bar would be helpful. —Preceding unsigned comment added by Ericg33 (talkcontribs) 22:18, 6 September 2008 (UTC)

William Stanley

He wasn't the inventor of transformer, but it was a redesigned version of Hungarian "ZBD" transformer for commercial usage. —Preceding unsigned comment added by (talk) 12:39, 27 December 2008 (UTC)

The first transformer

ZBD was the first transformer. The Basic principles works only with closed cores. The mathematic formula too. And the inventors named only the closed core coils as "transformers". Thats whi I spearate the history article, 1. First steps, experiments and results with coils, and the 2. : The transformer.

Improper heading: "The transformers"

"The transformers" is not a proper heading within the "Transformer" article because the heading has essentially the same meaning a the title of the article. --Gerry Ashton (talk) 21:39, 20 January 2009 (UTC)

A very interesting item on the [[Internet Archive] is The History of the Transformer by one F. Uppenborn, published in 1889. Faraday's 1832 apparatus was indubitably a transformer no matter what Uppenborn says, though Faraday didn't call it that and didn't have a convenient source of alternating current. Yes, the ZBD was a practical power transformer, but there were others before then. --Wtshymanski (talk) 01:26, 21 January 2009 (UTC)

Transformers before ZBD? hahaha It's just a tale. Please give a patent or other document before ZBD appeared. Solely the closed Core coil system = transformer. Open core or other previous systems are not transformers. ZBD was the first system wich was called as: the "transformer".Celebration1981

There were NOT exist Transformers before 1885

There were only colis. The ZBD was first structure what was called as tranformer. The basic priciple of tranformers (second point of the article) regards (and works) only for closed core coils.

Core flux see Electromagnetic compatibility handbook - Google Books —Preceding unsigned comment added by (talk) 23:00, 4 July 2009 (UTC)

It's OK to use the term "transformer" for something that was built before the word "transfomer" was coined. For example, the wheel article discusses wheels that wre made thousands of years before the English language originated, and so could not have been called wheels at the time. But that is not a problem. Or, for another example, we can use the word "dinosaur" for animals that were extinct before there was language at all!Ccrrccrr (talk) 18:22, 7 July 2009 (UTC)
Transformer (and its latter modernized variations) is a special (closed core) very high efficiency electric converter which was born in 1885. It has specific so called "transformer" circuit. (look the DEVELOPMENT picture). Former devices were unable to regulate voltage, and the most modern former induction coil system (Gulard & Gibbs) has a catastrophic efficiency (around 40%).
Imagine, the electronic energy go trough minimum 3-4 transformers to your computer and mobil-phone. 0.4*0.4*0.4 it's a very catastrophic result. the so called "transformer" coil-system reached the 97-99% by the turn of the century. It's inventor was Otto Bláthy. He had two assistants. They used foremost the famous formula, and different coil ratios. Only this ZBD or Transformer system was the first which based on clearly the formula.
Dr. Bláthy was a real genius, wasn't he? Excelent mathematican and physicist famous chess player. He had never boasted with his high scientific (academic) ranks and titles. Just an example: He knew the Austrian Emperor Franz Joseph, and met Queen Victoria in London because He was very very famous staghound breeder. His dogs were always the winner in international competitions. (Ironically the queen and the emperor did not know about his inventions and university career, they invited him for dinner, because of his dogs.) He regulary sold expensive staghounds for British and Austrian courts. Months later, queen Victoria suprised when read about the old invention of Bláthy. Before 1910 , emperor Franz Joseph invited Bláthy to his celebrations in every year. The emperor (who hate the electricity and electric wires which "defaced his Austrian and Hungarian cities and villages") read about Bláhy's inventions in a newspaper in 1910, when he realised who was Blathy, he became very furious, and never invited him again. --Celebration1981 (talk) 19:30, 7 July 2009 (UTC)
I do not agree that the term "transformer" only applies to high-efficiency closed-core power transformers. Air-core RF transformers and RF transformers based on ferrite rods are transformers too. --Jc3s5h (talk) 21:07, 7 July 2009 (UTC)
I think it may be right that the closed core transformer was invented in 1885 by Bláthy, and I think it is correct that this was a very important development, and that it should be documented in the article. However, in modern usage, the term transformer applies to air-core transformers, magnetic-core transformers with open flux paths, leakage transformers, etc. So we can't say that he invented the transformer, only that he dramatically improved it. That may be a more important accomplishment than inventing it. We should describe it as what it is and give credit for what it is, not try to define it as what it's not.Ccrrccrr (talk) 21:12, 7 July 2009 (UTC)

The Tranformer name did not exist in electro technology before ZBD. The electric converter was in usage. Bláthy was a mathematician, the latin term of "geometric transformation" was prevalent in mathematics. Bláthy copied that geometric term "trans-formation" into electrical engineering. The ZBD device and the new name "TRANS-FORMER" for the new electric converter became very famous and popular. From 1886, nobody called this revolutionary new voltage-regulator types of iduction-coil systems as "converter" anymore. Read old technologian books (in 19th century) ,calls "converters" the old induction coil systems, and they called transformers the new high efficiency systems which are capable to regulate voltage after 1885.

But read about the most modern "high-tech" system before 1885:

"In practice, several coils with a ratio near 1:1 were connected with their primaries in series to allow use of a high voltage for transmission while presenting a low voltage to the lamps. The inherent flaw in this method was that turning off a single lamp affected all the others on the circuit, and many adjustable coil designs were introduced in an effort to accommodate this problematic characteristic of the series circuit" [5]

ZBD could TRANS-FORM the voltage

The name :Transformer is a milestone, it refers only the post 1885 era. the Gaulard and Gibbs and other systems were called as in their original old name: "converters"

The correct definition for transformers:

Transformers = high efficiency induction-coil systems, which are capable to regulate voltage in itself.

This is the first way to build high efficiency devices which are capable to regulate the voltage. And only these type of devices work with the famous formula. Bláthy-formula is the other official name of this formula in Hungary, because : "Besides gear ratio based on ratio of number of turns, in the patents of transformer (protected by two patents) ..." ( He invented and patented foremost this formula. Therefore all former induction coil sets were NOT so called "transformers" ,they were just induction-coil systems. --Celebration1981 (talk) 07:44, 8 July 2009 (UTC) is a commercial site — solar energy products, and as such may not be considered a reliable source of historical technical information.
From K. Zipernowsky, M. Bláthy and O. T. Déri, Induction Coil, Patent No. US352105, U.S. Patent Office, 1886-11-02, retrieved 2009-07-08:
"Be it known that we ... have invented new and useful improvements in Induction Apparatus for Transforming Electric Currents, of which the following is a specification.
The object of the present invention is to solve the problem of distributing electrical energy in a practical and at the same time economical manner, and we attain this by inductional transformers for alternating currents with closed magnetic circuits.
Before entering into a description of our invention, we may premise that for the illumination of towns, as also generally in the case of electric current requiring to be distributed over long distances, the so-called 'secondary inductors' or 'transformers' are specially adapted, as it is possible, by the aid of this apparatus, to distribute this current in a cheap and satisfactory manner over great, almost unlimited distances." (Emphasis added.)
ZBD thus tell us that devices for "Transforming Electric Currents" — "so-called 'secondary inductors' or 'transformers'" — were already extant when they authored their patent application, that they were introducing "improvements" to such devices, particularly "closed magnetic circuits", and that their new design was not the first "Induction Apparatus" to bear the name "transformer". (Whether they had coined the name is irrelevant if it was in use before the "closed magnetic circuits" design was invented.)
Cheers, Rico402 (talk) 17:25, 8 July 2009 (UTC)

"'secondary inductors' or 'transformers'" — were already extant"

They refered for the previous inventions (Gaulard & Gibbs) which proved blind alley (because all previous systems had horror efficiency) All previous inventors used the converter word. The ZBD patent contained foremost the "Transformer" term. Please show me an older patent or older original source which mentioned (that time) the mathemathics term: "Transformer". You can't, (and you have never can). The 1886 USA patent of ZBD is not interesting, because the ZBD team patented it in many European countries. Foremost in Hungary in Januar 2, 1885. (Because patent office was closed for two weeks in Christmas and new Year) --Celebration1981 (talk) 17:58, 8 July 2009 (UTC)

Celebration1981, provide a modern source that defines "transformer" as you do. Nobody gives a damn what an anonymous internet poster thinks the modern meaning of "transformer" is.
Here is one modern definiton from The Art of Electronics (2nd ed., p. 28)

A transformer is a device consisting of two closely coupled coils (called primary and secondary).

--Jc3s5h (talk) 18:09, 8 July 2009 (UTC)

Before the ZBD everybody used only 1:1 coil ratio, because they didn't know the concrete mathematical relationships. "Here is one modern definiton from The Art of Electronics (2nd ed., p. 28)" It is too modern for that period, because the modern authors of this source simplifies the term. Why? Because nowadays nobody want to buid a induction-coil systems of Faraday-era . Boys, show me a pre 1885 original source or patent, which use the "Transformer" term. OK? (you can't, because transformation was a geometric term before 1885:))))) ) Bláthy and the invention of "Z.B.D." is the greatest name, and the turning point in the history of the realization of electric transmission. And the spread of Electric transmission systems caused the biggest change in human life and in the History of Human civilization in this planet. --Celebration1981 (talk) 18:25, 8 July 2009 (UTC)

It was similar great invention as Kálmán Tihanyi's invention. (my Rico friend knows it yet:)))))) Previous inventors made and made their blind-alley inventions. Kálmán Tihanyi recognized the indispensability necessity of the collection / storage of charges of photo-electrons in cameras from 1920, (all later sensors like CCD and CMOS based on this idea until this day but they operate different moderner technology, without storage idea collection of electric charges the sensors would be too dark/blind) He invented the practical realization os charge-storage for vacuum tubes in 1924(!!!), published it in 1925, and he made a very detailed patent in 1926 about his camera radio transmission and receiver system. (His display and transmission patents were far modern than other inventor's of the era) And what happend? Nobody belive in early 1920's in the necessity of charge storage, until when a letter arrived from British Air Ministry. They trust and supported Tihanyi's ideas, B.A.Ministry and Royal Air Force could build the first modern TV-systems with excelent quality in their "aerial-torpedos". The success took a wind. From 1929 the pompous RCA and other big companies tried to built charge-storage systems (with capacitors hahahaha:))) but failed.... They had to buy Tihanyi's patents :))))))--Celebration1981 (talk)

Blah, blah, blah... How pathetic...

Re "'secondary inductors' or 'transformers'" — were already extant", Celebration1981 contradicted his own argument. ZBD "refered for the previous inventions" (sic), he writes. Yes they did, and they called them "transformers". (Patent No. US352105, U.S. Patent Office, 1886-11-02, retrieved 2009-07-08.) If he disagrees, then let him provide the documentary evidence. He asks that I provide "an older patent or older original source which mentioned (that time) the mathemathics term: 'Transformer'", yet he fails to provide any document to support his claim. Btw, "transformer" isn't a "mathemathics" (mathematical?) term, at least in the context of this article.

The definition in TAoE (which I also have) doesn't specify core design, thus leaving the matter open.

"Transformer" in the Concise Encyclopedia of Science and Technology (Third Edition, Sybil P. Parker, ed. McGraw-Hill, Inc., 1994, p. 1937) begins,

"An electrical component used to transfer electrical energy from one alternating-current (ac) circuit to another by magnetic coupling. Essentially it consists of two or more multiturn coils of wire placed in close proximity to cause the magnetic field of one to link the other." Again, core design is not specified.

"Converter" is described on page 473 of the same text as,

"A device for processing alternating-current (ac) or direct-current (dc) power to provide a different electrical waveform. The term converter denotes a mechanism for either processing ac power into dc power (rectifier) or deriving power with an ac waveform from dc (inverter). Some converters serve both functions, others only one."

University Physics, 6th ed. by Sears, Zemansky and Young (Addison-Wesley, 1983) give us the following:

"In principle, the transformer consists of two coils electrically insulated from each other and wound on the same iron core. An alternating current in one winding sets up an alternating flux in the core, and the induced electric field produced by this varying flux (see Sec. 33.2) induces an emf in the other winding." (Sec. 33-2 is a discussion of Faraday's law.)

In all three examples, a closed-core is not given as a defining attribute of a transformer. Two or more coils capable of mutual inductance is the defining attribute. Keep in mind that this is the English version of Wikipedia, therefore English definitions apply.

Rico402 (talk) 21:39, 8 July 2009 (UTC)

Agreed. Celebration1981, we don't disagree about the importance of the invention--there's no need to keep hammering on that. The issue here is only terminology. As Rico says, we are writing in (modern) English, so we go by the definitions he cites. What terminology was used before the 1880s might be an interesting side note, but that's only a side note. See my examples about wheel and dinosaur, above.Ccrrccrr (talk) 21:48, 8 July 2009 (UTC)
Indeed! All this nonsense over semantics. Rico402 (talk) 22:58, 8 July 2009 (UTC)

Again, there is no original article or notice or patent which mentioned the "transformer" before 1885. You can't find, because it does not exist. Only closed magnetic circuits can transform the AC energy (In the point of view of electric transmission systems and electric power stations, it is not interesting that air-core audio and high freq. radio transformers have not closed cores.) The ZBD with the formula changed the history of eletric engineering, and the history of mankind. 1885 was not a simple "important" or "very important" date, but it was a determinative turning point. --Celebration1981 (talk) 07:09, 9 July 2009 (UTC)

The other important thing in ZBD, it was the first parallel circuit type induction coil system (and they designed parallel circuit transsmission systems). The detailed articles mentioned this "parallel circuit ZBD system" was very important, because all former systems were "series circuit" systems and therefore problematic. Zipernowsky invented that primer and secunder coils must stand in parallel type circuit for every consumers (like electric bulbs motors etc). Why was it so important recognition in history of transformers?


Mr. William Grove must be mentioned in early period of the article, he was the inventor of ferrite core in induction coils. Can you find detailed articles about his developments?--Celebration1981 (talk) 07:41, 9 July 2009 (UTC)

"(In the point of view of electric transmission systems and electric power stations, it is not interesting that air-core audio and high freq. radio transformers have not closed cores.)" BULLSHIT. The title of the article is "Transformer", not "Electric power distribution transformers. --Jc3s5h (talk) 09:39, 9 July 2009 (UTC)

Jc3s5h how childish are you, Don't delete my answers again , everybody can see your deletion in the history of discussuion. Do you play the wags ?

"Jc3s5h is no more than just a little rebellious teenager, that's why he swore. My illiterate friend, in 1885 the main problem was the transmission of electric energy, and the transformation in audio technology or radio technology was not exist or was not priority." --Celebration1981 (talk) 11:09, 9 July 2009 (UTC)

I request other readers to consider whether a WP:Request for Comment on Celebration1981's insults is called for. --Jc3s5h (talk) 12:07, 9 July 2009 (UTC)

Hahaha, your "Bullshit" insult is more hurtful, than my simple allusion to your young age. Amen. --Celebration1981 (talk) 12:23, 9 July 2009 (UTC)

Britannica is an encyclopedia for the general public; it is NOT by any means the definitive word on any subject. University Physics and The Art of Electronics are academic texts written by professor who are renowned in their fields and are used in physics and engineering classes at major universities around the world. (The Art of Electronics is purportedly the most widely used electronics text in engineering classes in the US, possibly the world.) University Physics devotes over 250 pages to electrostatics and electromagnetism. (And a couple more texts are required if you study quantum theory related to those subjects.) How many pages does Britannica devote to electromagnetism? Like any work written for the general public, it is "dumbed down" so as to be comprehensible to a wide audience, and by necessity offers only brief summaries of the subjects covered. It would be laughably absurd to use Britannica as a text in a class at a university in any industrialized country. If you had attended university you would know that. As usual, you know not of what you write. Rico402 (talk) 22:44, 11 July 2009 (UTC)

For anglocentric American nationalist Rico: "it is "dumbed down" so as " Do you think that all encyclopedias are wrong in all country? :)))) Simple induction coils are not transformers, as you think, and that your shorter primitive simplistic definition sounds as a "dumbed down" definition . Do you know what the tranformer means? It is a latin word. Itself the meaning of the word exclude that devices without changing/converting the voltage are trans-form-ers. --Celebration1981 (talk) 05:04, 12 July 2009 (UTC) "And a couple more texts are required if you study quantum theory related to those subjects" Quantum theory started by a German Max Planck, but nobody knew its real mathematical background therefore it remained just a semi-science, until a Hungarian János Neumann made it. Lot of famous scientist of the era tried to made the mathematical background of the Q.theory but its proved to difficult for them. Neumann redefinied the definitions, he pointed out serials of former serious errors. He made Q. theory to a calculable science which made it a practicable science for industry. He invented the famous game theory and designed the world-famous ENIAC digital computer too.(ENIAC, short for Electronic Numerical Integrator And Computer,[1][2] was the first general-purpose electronic computer. It was a Turing-complete, digital computer capable of being reprogrammed to solve a full range of computing problems.[3] ENIAC was designed to calculate artillery firing tables for the U.S. Army's Ballistic Research Laboratory, but its first use was in calculations for the hydrogen bomb. When ENIAC was announced in 1946 it was heralded in the press as a "Giant Brain". It boasted speeds one thousand times faster than electro-mechanical machines, a leap in computing power that no single machine has since matched. This mathematical power, coupled with general-purpose programmability, excited scientists and industrialists.) Neumann was the main mathematican in Manhattan Project. Other famous Hungarian was Jenő Wigner often reffered as the father of quantum mechanics. Other famous Hungarian: Leó Szilárd his invention changed the basis of nuclear science: he invented the nuclear chain reaction and invented the nuclear reactor (and he invented with Wigner the first nuclear power station) as well as the first Particle accelerator. Therefore the nuclear physics became a practicable/utilizable science for mankind. As the inventor nuclear chain reaction, he realised foremost the atomic-bomb, he made the basic "Cutaway Drawing" of the first atomic bomb. He asked Albert Einstein to write letter to president Roosevelt for the realization of a concrete nuclear Bomb. In Manhattan project dosens of scientist and hundreds of engineers worked for the realization of Szilárd's idea: a working atomic bomb from 1939-1944. An other Hungarian Ede Teller invented the H-bomb. And it is just particle quantum / nuclear physics. It is just a branch of physics. We had dosens of similar great scientists in other branchs of the physics and natural sciences. The exaggeratedly anglocentric Rico have never heard about these scientists. The expert historians of natural sciences are always shocked about great number of Hungarian scientists, how is it possible for such a little country.

What said the Italian Enrico Fermi about Hungarians (the Marthians):

--Celebration1981 (talk) 08:43, 12 July 2009 (UTC)

Civil discussion on terminology before 1885

The above discussion on whether to use the word transformer for devices without closed core made before 1885 has degenerated to the point that I think we need to draw a line and start fresh. Let's review the guidelines in Wikipedia:Civility and try to keep this discussion within them. It's very hard to find the actual content in the long section above, what with profanity, personal insults, rambling tangents, etc.Ccrrccrr (talk) 16:44, 9 July 2009 (UTC)

As I see it, the situation is this:

  • We agree that in modern terminology transformer is used now for closed-core, air-core, and open-core devices.
  • We agree that the term transformer was not used before 1885.
  • We agree that closed-core transformers were invented in about 1885.
  • We agree that the invention of closed-core transformers was extremely super-duper (insert other superlatives here) important and more.

The open question is whether we should use modern terminology for pre-1885 devices or use the original terminology. Maybe we can come up with a compromise on that.

But first, can we agree to stop discussing that four bullets above? As far as I know, nobody dispute any of them. Then we can focus on forming a consensus on the unresolved questions--I think there's only one.Ccrrccrr (talk) 16:44, 9 July 2009 (UTC)

You forgot to mention the invention of the famous mathematics FORMULA!!! Before the ZBD, all coil ratio was 1:1 !!! --Celebration1981 (talk) 17:33, 9 July 2009 (UTC)

Thanks. I'm OK with that too--ZBD was the first use of non-1:1 turns ratios and the first use of to describe transformer behavior. Anyone disagree with that?Ccrrccrr (talk) 17:47, 9 July 2009 (UTC)

I agree.--Celebration1981 (talk) 18:10, 9 July 2009 (UTC)

I just read the Uppenborn "History of the Transformer" [3]. It turns out that two of the agreed upon things I wrote are not true:
  • Faraday's own experiment used a closed core. See Fig. 2 in Uppenborn, or [4]. It's not that it had never been done before--it was just the people trying to build practical transformers didn't understand how a closed core worked.
  • The idea of turns ratios other than 1:1 was fairly well known before ZBD. See p. 9-10 in Uppendorn.
However, this doesn't in any way reduce my sense that ZBD's invention was critical. An important part of their invention was how to use transformers in the electrical distribution system we use today. p. 55-57 of Uppenborn make this very clear. Ccrrccrr (talk) 22:14, 10 July 2009 (UTC)
Another good source on this: "Creating the twentieth century: technical innovations of 1867-1914"by Vaclav Smil, 2005 [5]Ccrrccrr (talk) 22:22, 10 July 2009 (UTC) --Celebration1981 (talk) 06:42, 11 July 2009 (UTC)

Haha, I don't know that Faraday knew the electric generator:))) Faraday did not know that AC voltage is trans-form-able with induction coils. Nobody know the magic formula before Bláthy. This new formula for transformer was protected in their patents. All of the scientific world unanimously stated that closed-core is one of the mindless invention of the world, therefore the ZBD had to go to an European exhibition-journey with the new device to prove their fair name. Faraday's device was no more that time , than a demonstrative device for inductions. Therefore it is farfetched and impossible to call it as transformer. Please read your book very thoughtfully! You can found very important informations about Bláthy and the team in page 50 and 59. --Celebration1981 (talk) 06:50, 11 July 2009 (UTC)

I added important and more precise infos with source :Ottó Bláthy was suggested the advance of closed-cores, shunt connection was the idea of Károly Zipernowsky, experiments were performed by Miksa Déri

The other important thing was their new power distribution system.

The real transformer, and all the point of reference is the "ZBD" in Uppenborn's book (see page 4-5),the other (decisive) difference: Faraday's device had poles , the real transformer ZBD (which was used for real voltage trans-formation) had no poles.

--Celebration1981 (talk) 11:24, 11 July 2009 (UTC)

According to your imprecise (unreasonable) term: every induction coil is transformer. But in most countries, the transformer means a device which can trans-form AC electricity, and not a simple device for proving of induction. But look Britannica about Transformer definition: "device that transfers electric energy from one alternating-current circuit to one or more other circuits, either increasing (stepping up) or reducing (stepping down) the voltage." The definiton is the same as the definition of Hungarian and German and Italian encyclopedias. Sorry I speak fluently only in German Italian and of course Hungarian, (I've never learned English, therefore I read mostly German Hungarian Italian sources and books) Britannica is a symbol and determinant in English speaking world, it contained the so-called "official" scientific (academic) viewpoint, because it is edited by real (academic ranking) scientists. I believe that you have very very good books about electro-technology, but that books are not "official" (academic) opinions or definitions.

No, Faraday did not know that AC voltage is trans-form-able with induction coils, he had no concept about the regulating (or TRANSFORMING) AC voltage. I must repeat my previous statements :The real transformer, and all the point-of-reference is the "ZBD" in Uppenborn's book (see page 4-5),the other (decisive) difference: Faraday's device had poles , the real transformer ZBD (which was used for real voltage trans-formation) had no poles.

You always cited the (open and air core) radio audio transformers, which based on very high freq. currents, but nobody interested about these radio and audio technology in the pre 1885 era. And nobody knew that high freq. currents behave very different than tha low freq. so-called generator-currents. Stanley created a patent only for America

--Celebration1981 (talk) 12:34, 11 July 2009 (UTC)

Thanks for the new edit. I agree that their invention of the ac power distribution system that is still used today is very important, as well as their transformer work.
You replied to my two bullets above with Haha, but I don't see that you disagree with either of them. So let me try again--now I'll repeat my four bullets from above, modified to be more accurate.
  • In modern terminology transformer is used now for closed-core, air-core, and open-core devices.
  • The term transformer was not used before 1885.
  • The value of a closed core was recognized by Faraday, but was not understood by people who were trying to develop practical applications in power distribution and lighting systems before 1885, when Bláthy realized it was superior.
  • ZBD's invention--both of practical transformers and their use in the modern ac distribution system-- was extremely super-duper (insert other superlatives here) important and more.
Faraday understood electromagnetics well enough to know the advantage of a closed core, but he had no concept of the usefulness of his device in ac power systems (he had no concept of ac power systems).
This has all be an attempt to clear the air so that we could focus on whether to use the word transformer or not. So let's consider whether Faraday's device should be called a transformer. Certainly the term had not been invented yet, but the "dinosaur" and "wheel" arguments dispense with that argument. Uppendorn argues that it's not a transformer because it's 1:1. If we use modern terminology, the term transformer includes lots of 1:1 devices. The argument that it had poles, and therefore wasn't a transformer, is incorrect--the diagrams of square-core transformers used to illustrated our article have poles just like the Faraday device. We could argue that Faraday had no concept of using it in an AC distribution system, but that would be only an argument that it wasn't a power transformer, not that it wasn't a transformer. As illustrated by our article, there are many different application of transformers.Ccrrccrr (talk) 12:12, 11 July 2009 (UTC)

Stanley created a patent only for America. There was a race for the licence rights about transformers and the E. transmission system, and which was won by General Electric (lead by T. Edison), because Mr. Edison was quicker than Mr. Westinghouse, and Edison's agents arrived earlier to the licence and patent owner: the GANZ Company. The Ganz Company sold all rights to General Electric for the whole American Continent. Westinghouse had to pay for licence-expense to G.Electric It was a great triumph over Westinghouse. --Celebration1981 (talk) 16:28, 11 July 2009 (UTC)


According to your imprecise (unreasonable) term: every induction coil is transformer. But in most countries, the transformer means a device which can trans-form(regulate) AC electricity, and transformers are not a simple device for demonstrating the induction. But look Britannica about Transformer definition: "device that transfers electric energy from one alternating-current circuit to one or more other circuits, either increasing (stepping up) or reducing (stepping down) the voltage." [6] The definiton of tranformer is the same as the definition of Hungarian and German and Italian encyclopedias. Sorry I speak fluently only in German Italian and of course Hungarian, (I've never learned English, therefore I read mostly German Hungarian Italian sources and books) Britannica is a symbol and determinant in English speaking world, it contained the so-called "official" scientific (academic) viewpoint, because it is edited by real (academic ranking) scientists. I believe that you have very very good books about electro-technology, but that books are not "official" (academic) opinions or definitions. --Celebration1981 (talk) 17:32, 11 July 2009 (UTC)

All encyclopedias are not wrong, but all those published for general audiences are inadequate as source material for academic or scholarly articles, as well as some technical articles written for a non-academic readership. And I don't contend that all simple induction coils are transformers, nor have I ever argued that they were. And I don't wish to engage in a heated debate or editing war on the issue. In fact, between 22 March and 25 March, I removed the offending word “transformer” entirely from the “First steps…” subsection. My concern was that to describe induction coils as transformers would unnecessarily confuse the average reader. Although I may disagree with some of your assertions, we are in agreement that induction coils should not be identified as transformers in the “First steps…” subsection. Air core and other types of transformers that don't conform to the "conventional" definition of a transformer, i.e., ZBD-type designs, should be relegated to the later sections of the article. I'm hopeful that we can all agree on this.
My comments above regarding the formal (i.e., not conventional) definition of "transformer" were intended to edify you and others of the folly inherent in relying on reading materials intended for the general public to address specialized fields of study, rather than on academic or scholarly texts, articles, reports, etc. written by and for professors, scientists and engineers. I am both a scientist and an engineer, and I take matters of technical accuracy very seriously. This is what prompted the aforementioned comments. But I also realize that "technical" or "formal" definitions of various terms are often not suited for the general reader, for which Wiki articles are intended.
My earlier comments regarding the application of the word "transformer" only noted that based on the available sources — Uppenborn and the US patent for the ZBD device, it may have already been in use prior to the original ZBD patent to describe mutual induction coils used to provide a low voltage from a high voltage source. You have yet to provide any contradictory evidence. Why not translate the relevant passages of the original ZBD patent into English? Perhaps that will settle the matter, and you need not be concerned about errors in spelling or grammar, as they likely will not alter the fundamental import of the aforementioned passages.
I should also mention that Uppenborn remarks on page 39 that a step-up induction coil was not considered a transformer as "the word is used to-day [1889], that is, as an induction apparatus, which converts high into low tension currents." If Uppenborn is correct, then by 1889 all induction coils used to provide low voltages from high voltage sources were commonly called transformers. (That doesn't suggest that the terminology in use was correct, just common.) As he excludes step-up devices from the terminology of the time, I think it best we not rely on Uppenborn's definition of what is a transformer.
Re: "Do you know what the tranformer (sic) means?" First of all, I find such questions rude and inappropriate; they seem designed to give offense, as also seems to be the case in your frequent use of "haha" and "laughingcons", i.e., ":)))". But my reply is this: Yes, do you? The word "transformer" was common hundreds of years before it was chosen to describe an electrical apparatus. All manner of natural, verbal or mechanical systems or devices may cause transformations, thus they are all properly defined as "transformers", i.e., things that cause transformations. Also, while not meaning to give offense, might I suggest that you please refrain from further heated semantic debates, as by your own admission you are only marginally fluent in English. Forsaking modesty, I would note that I am particularly fluent, and that my skill in authoring technical and non-technical works has not only been remuneratively rewarded, but has frequently garnered praise from highly-respected professors, employers, colleagues, etc. For you to question my knowledge of the English language, and the proper use thereof, I find personally offensive. Please let us be polite and respectful in our discourse. Kind regards, Rico402 (talk) 12:21, 12 July 2009 (UTC)

Stanley's 1886 commercial version of the Z.B.D. transformer.

The image with the caption "Stanley's 1886 commercial version of the Z.B.D. transformer" is not of a ZBD-type transformer, but of two (of 3) open-core induction coil designs for which Stanley had applied for a patent on 23 Oct. 1885, and was granted and assigned to George Westinghouse on 21 Sept. 1886 as US patent no. 0349611. The novelty of these designs was the inclusion of a non-magnetic adjusting screw in the core gap for varying the induced emf in the secondary winding. Whether it began life as a closed-core design I don't know, but there is no mention of ZBD or of the device being a transformer in the patent. And of course there is no mention of a "core from interlocking E-shaped iron plates."

It's clear that the image doesn't conform with the accompanying text, and indeed belongs in the previous section. Thus this bit requires immediate attention, but I don't have ready access to the article referenced here: Coltman, J. W. (January 1988), "The Transformer", Scientific American: 86–95, so I haven't attempted any corrections other than to add a ref for the image.

Cheers, Rico402 (talk) 12:37, 13 July 2009 (UTC)

The answer is easy. Edison's (G.Electric) agents bought the full patent & licence rights of ZBD and the electric distribution system for the Whole American Continent. Westinghouse had to buy, and Westinghouse had to pay royalty for G.E. after every sold transformers. It caused great incomings for Generel Electric in the age of early electrification (and some years later, Edison gave up with the idea of DC. ) --Celebration1981 (talk) 17:28, 13 July 2009 (UTC)

You reply has nothing whatsoever to do with the problem cited above, which is this: The image identified as "Stanley's 1886 commercial version of the Z.B.D. transformer" shows induction coils with open cores, not ZBD-type transformers, and certainly not cores "from interlocking E-shaped iron plates".
These drawings are from Stanley's patent for open-core induction coils with variable gaps; they do not match the text of the article. Rico402 (talk) 22:18, 13 July 2009 (UTC)
Yes, the article is a mess. But it was the Westinghouse group, including Stanley, who moved from the ring core, seen in both these adjustable gap pictures and ZBD, to "interlocking E-shaped iron plates," which is the design still in use today. They were motivated by manufacturability and perhaps by avoiding the ZBD patents. See ref 10, Smil. Sorry I have no time to work on this this week.Ccrrccrr (talk) 14:20, 16 July 2009 (UTC)
True enough... Do we even need the image of Stanley's induction coils? Unless it's in the text it should be deleted. I'll see if I can't get the Westinghouse closed-core E-shaped plates design back in. Rico402 (talk) 20:20, 16 July 2009 (UTC)
Okay, done for now I guess. But not sure which "design was first used commercially in 1886", and the appropriate ref; may need correction. Rico402 (talk) 22:00, 16 July 2009 (UTC)

Faraday description

Celebration reverted

Michael Faraday discovered the principle behind transformers, Faraday's induction law, in 1831 and did the first experiments with induction between coils of wire, including building a pair of coils on a toroidal closed magnetic core.

with the comment

Faraday invented the induction phenomenon, but without recognition of its future role in manipulating EMF. He had not idea what is transformer. Transformer is not simple induction coil. STOP the LIE!

after waiting 25 hours and 9 minutes from a previous revert in order to skirt the three revert rule.

The comment used to support the revert probably reflects a lack of careful reading and full comprehension of the text in question. The removed does not claim that Faraday invented the transformer. It does not claim that Faraday built a transformer. It does not claim that Faraday had any understanding of the possible applications of transformers. It does not claim that Faraday used the word transformer. It only claims that

  1. Faraday discovered the principle of induction--a claim that is in the new version, so is presumably accepted by Celebration.
  2. Induction is the principle behind transformers. This is also hard to deny. See the Basic principles section of the article.

Celebration, please let us know which of these you disagree with and why.Ccrrccrr (talk) 20:20, 22 July 2009 (UTC)

Origin of term

I'm not sure the origin of the term transformer is particularly notable content, but to fend off efforts to insert bogus claims about it, here's a source for the use of the French version of the term in 1881 [6], La physique moderne: les principales applications de l'electricite by, Édouard Hospitalier, Published by Masson in 1881. I cited the 1882 English translation in the article. -Ccrrccrr (talk) 21:07, 22 July 2009 (UTC)

"We designate by the term electric transformers apparatus in which electricity is no longer produced directly, but is transformed and changes its properties." (Emphasis added.) --Hospitalier, Édouard, 1882, The Modern Applications of Electricity, Translated and Enlarged by Julius Maier. New York, D. Appleton & Co., p. 103. Rico402 (talk) 02:28, 23 July 2009 (UTC)

It was a reedited (after 1885) version, translated from French to English . The original French text did not contain the word "transformer" yet.--Celebration1981 (talk) 08:30, 23 July 2009 (UTC)

"Nous avons classé souls le nom un peu nouveau, mais parfaitement reationnel, de transformateurs électriques des appareils dans lesquels l'électricité n'est plus produite directement, mais se transforme et changes ses proprietés." (Emphasis in original.) --Hospitalier, Édouard , 1881, Les Principales Applicatrions de L’électricité, Paris, G. Mason, ed., p. 92. Rico402 (talk) 09:45, 23 July 2009 (UTC)
Celebration provides no evidence. But the French copy google scanned in the link I provided above has an 1881 publication date, an Oct. 1880 signature date in the preface, and a library ownership card pasted inside the front cover showing that a library acquired it in Dec. 1881.
ZBD's accomplishments were fabulous. Their solid engineering makes the prior inventors look like bumbling idiots. Why can't we let their real accomplishments shine without needing to attribute everything to them?Ccrrccrr (talk) 11:37, 23 July 2009 (UTC)

ZBD was the The Saviour in AC technology, because it had great 97-99% efficiency and shunt connection. And it was patented with a revolutionary new power distribution system. Before ZBD the AC had no real chance to rival with Edison's DC system. --Celebration1981 (talk) 08:45, 23 July 2009 (UTC)

  1. ^ a b c Cite error: The named reference flanagan_p2.1 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference J.26P_p2-3 was invoked but never defined (see the help page).
  3. ^ Hindmarsh. Electrical Machines and their Applications, 4th edition. pp. pp142–143. 
  4. ^ a b Say. Alternating Current Machines, Fifth Edition. 
  5. ^ Uppenborn, F. J., History of the Transformer, E. & F. N. Spon, London, 1889.
  6. ^